Consolidated Statements Of Cash Flows - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016
Cash flow from operating activities:
Net income	$ 43,303	$ 29,098
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	35,915	38,217
Stock-based compensation	13,726	13,497
Tax expense from deferred income taxes	(875)	(2,927)
Changes in operating assets and liabilities	(7,284)	2,659
Net cash provided by operating activities	84,785	80,544
Cash flow from investing activities:
Capital expenditures	(15,727)	(20,970)
Capitalization of internally developed software	(24,816)	(15,406)
Additions to other intangibles	(1,124)	(689)
Acquisitions, net of cash received		(549)
Purchases of short-term investments	(52,807)	(5,008)
Sales and maturities of short-term investments	21,017	31,734
Net cash used in investing activities	(73,457)	(10,888)
Cash flow from financing activities:
Proceeds from revolving line of credit		15,000
Principal payments on revolving line of credit		(12,000)
Proceeds from issuance of common stock	15,407	14,830
Repurchase of common stock		(5,635)
Dividends paid	(54,595)	(51,273)
Net cash used in financing activities	(39,188)	(39,078)
Effect of exchange rate changes on cash	5,727	3,554
Net change in cash and cash equivalents	(22,133)	34,132
Cash and cash equivalents at beginning of period	285,283	251,129
Cash and cash equivalents at end of period	$ 263,150	$ 285,261